This invention relates to the field of devices for separating rocks, rubble, gravel and debris from soil and in particular to a selectively pivotable rigid mesh screen pivotally mounted on a supporting frame and adapted for use with skid-steer style front end loaders.
It is well known that screened top soil has a certain resale value for use in landscaping and construction. During such construction it is often the case that during excavation or during land clearing or the like that quantities of top soil have to be moved and distributed in the construction site or otherwise removed from the construction site, there being a later need for screened top soil once construction is complete. It is now common that on such construction sites that relatively small skid-steer front end loaders such as sold under the trademark Bobcat are employed for minor excavation, distribution of top soil, and loading of top soil into containers for removal. Consequently, there exists a need for a robust portable soil screen device which is compatible with the use of skid-steer style front end loaders to efficiently and economically screen rocks, rubble, debris, and large particle size gravel from otherwise readily reusable top soil found for example existing on a construction site.
In the prior art, applicant is aware of U.S. Pat. No. 4,505,812 which issued to Lees for a Sieve Screen Deck on Mar. 19, 1985. What Lees discloses is a sieve screen deck having a plurality of wedge wires connected to an array of backing bars running longitudinally of the screen parallel to its fall line. The screen is connected to a frame so as to include a resilient means accommodating vibrating and flexing of the screen during rapping or vibration of the screen so as to screen solid particulate matter using slots having a width of from ten microns to four millimeters. The screen is not rotatably mounted to the supporting frame. Other patents also rely on vibrating a screen for example such as disclosed in U.S. Pat. No. 5,392,925 which issued to Seyffert on Feb. 28, 1995 for a Shale Shaker and Screen, and in U.S. Pat. No. 5,641,071 which issued Read et al. on Jun. 24, 1997 for a Convertible Material Separating Apparatus and Convertible Kits. Applicant is also aware of U.S. Pat. No. 6,059,119 which issued to Davis on May 9, 2000 for a Rock Screed Bucket. Vibratory mechanisms such as taught in these patents add complexity, weight and cost to the manufacturer of such screening devices.
Applicant is also aware of devices for screening which employ the use of inclined screens, for example, Canadian Patent No. 1,144,111 which issued Apr. 5, 1983 to Simbas for a Grading Plant, published International Patent Application No. PCT/US97/01722 filed Jan. 29, 1997 by Curtis for a Curved Freestanding Garden Sieve, U.S. Pat. No. 1,424,451 which issued to Crandall on Aug. 1, 1922 for a Combined Sand and Gravel Screen, and U.S. Pat. No. 1,510,742 which issued Oct. 7, 1924 to Gutleben for a Sand and Gravel Screen. Neither Simbas, Curtis, Crandall nor Gutleben disclose an inclined screen pivotally mounted along its upper edge to a support frame and adapted for complimentary ease of use with a skid-steer style front end loader bucket.
In summary the soil screening device of the present invention includes a screen frame having a screening surface, and a supporting frame. The supporting frame may have rearwardly disposed rigid uprights supporting the screen frame. The screen frame is pivotally mounted to a first upper member mounted at an upper end of the uprights, for pivoting between a lowered position and an elevated position. The supporting frame has a base frame extending forwardly of the uprights. Upper members of the base frame have at least one wedge selectively positionably mounted thereon, for example atop the upper member of the base frame. The wedge or wedges are positionable to engage a lower edge of the screen frame when in the lowered position bearing down on an upper inclined surface of the wedge or wedges. The wedge or wedges are selectively positionable relative to the upper members of the base frame so as to selectively adjust an angular orientation of the screen frame relative to the uprights.
The uprights define a first rear opening between the uprights and under the screen frame. The opening is sized to accept a front end loader bucket therethrough for engagement of the bucket with an underside of the screen frame. File base frame defines a second rear opening below the first rear opening. The second rear opening is sized to accept the bucket therethrough for engagement of the bucket with cross members of the base frame. The base frame may be substantially a parallelepiped and the first and second rear openings may be substantially rectangular. The uprights may be a parallel and spaced apart pair of uprights bounding opposite ends of the first and second rear openings.
The cross members may include at least a rear-most cross member adjacent the uprights. At least one rigid member may depend downwardly from the rear-most cross member for releasably locking behind a rear edge of the bucket when the bucket is fully inserted into and through the second rear opening.
The upper members may include at least one channel member forming an upwardly opening channel in which a wedge is slidably mounted. The at least one channel member may be perpendicular to the uprights, and may be orthogonal to the first rear opening. The at least one channel member may include locking means for releasably lockably positioning wedges along the at least one channel member. The at least one channel member may be a parallel pair of spaced apart channel members mounted adjacent opposite ends of the base frame, and consequently at least one wedge may be a pair of wedges mounted in the channel members.
The first upper member may be a horizontal cross bar between the uprights. An upper edge of the screen frame may be parallel to the horizontal cross bar and pivotally mounted thereto by hinge means. A deflecting bar may be mounted along the upper edge of the screen frame so as to at least partially cover the hinge means.
The base frame may be sheeted across the front thereof. An upper forward edge of the base frame may be bevelled and sheeted so as to extend beneath the lower edge of the screen frame when in the lowered position to deflect debris falling from the screening surface forwardly from the base frame.